1. Field of the Invention
The present invention relates to flexible polypropylene resin compositions with good weather resistance for use in surface protection, and to films or sheets made from them.
2. Description of the Background
Heretofore, vinyl chloride-based resins have been used for surface-protective films for construction materials, furniture, etc. However, because of the problems with the resins in that the plasticizer in them is toxic and that they generate toxic gas when their wastes are incinerated, the resins are being substituted with polyolefin resins.
Surface-protective films or sheets of polyolefin resins are known, for example, in Japanese Patent Application Laid-Open (JP-A) Hei-5-92514 in which is disclosed a technique of adding a hindered amine light stabilizer (hereinafter referred to as HALS) singly or as combined with an ultraviolet absorbent (hereinafter referred to as UVA) to surface-protective films comprising a polyolefin/adhesive layer for vehicles, steel pipes and others, for the purpose of improving the weather resistance of the films.
In JP-A Hei-6-212033, disclosed are polyolefin resin compositions comprising a high-molecular weight HALS (molecular weight: not smaller than 2000) and UVA. They say that the coatability of the compositions in high-solid-type coating is good and the weather resistance of the films of the compositions is good.
However, surface-protective films or sheets of conventional polyolefin resins for construction materials, furniture and others are not always satisfactory with respect to their surface-protective effect, apparent quality, etc. Surface-protective films or sheets of flexible polypropylene resins having an adhesive layer or an ink layer formed thereon are problematic in that the discoloration resistance, the weather resistance and the adhesion retentiveness of the ink layer and the adhesive layer are not always satisfactory even though the additives noted above are added thereto. The present invention is to provide flexible polypropylene resin compositions of which the moldings such as films or sheets have good weather resistance, and to provide films or sheets of the compositions. The invention is also to provide flexible polypropylene resin compositions capable of being formed into surface-protective films or sheets as combined with an ink layer and/or an adhesive layer formed on their inner surface, in which the ink layer has good discoloration resistance and weather resistance and the adhesive layer has good adhesion retentiveness and weather resistance, and to provide surface-protective films or sheets of the compositions of which the inner surface is optionally supported by a substrate film or sheet.